falconGitHub

avoid-positional-fields-in-records

Same as avoid_positional_fields_in_records in Pyramid Lint

Group
Style
Path
lint/style/avoid-positional-fields-in-records
Default
Off, opt in
Origin
Pyramid Lint
Rule
113 of 512

Flags positional fields in record types.

Positional record fields are accessed as $1, $2, and so on, which convey nothing about what each field means and break silently when fields are reordered. Named fields (({int x, int y})) document intent at both the declaration and every use site. The check recurses through type arguments and nested record and function types, so a positional field buried inside a generic is still reported.

Invalid

example.dartdart
class RecordExamples {
  /// Positional fields in record literal
  void example1() {
    final record = (1, 'hello');
    print(record);
  }

  /// Positional fields in record type return
  (int, String) getInfo() {
    return (42, 'answer');
  }

  /// Positional fields in record type parameter
  void processRecord((int, String) data) {
    print(data);
  }

  /// Positional fields in record type variable
  void example2() {
    (String, bool, int) tuple = ('test', true, 5);
    print(tuple);
  }

  /// Positional fields in record literal with multiple
  void example3() {
    final result = (1, 2, 3, 'four');
    print(result);
  }
}

// Regression: a declaration nested in a labeled block or a closure body must
// still be checked — a hand-rolled walk skipped those statement forms.
void containersRegression() {
  lbl: {
    final inLabeled = (1, 2);
    print(inLabeled);
  }
  final closure = () {
    final inClosure = (3, 4);
    return inClosure;
  };
  print(closure);
}

typedef Pair = (int, String);

void typePositions(Object value) {
  final cast = value as (int, String);
  final test = value is (int, String);
  final callback = ((int, String) pair) => pair;
  print([cast, test, callback]);
}

final callback = () {
  final pair = (1, 2);
  return pair;
};
Avoid positional fields in records. Use named fields instead.
3 void example1() {
4 final record = (1, 'hello');
Avoid positional fields in records. Use named fields instead.
8 /// Positional fields in record type return
9 (int, String) getInfo() {
Avoid positional fields in records. Use named fields instead.
13 /// Positional fields in record type parameter
14 void processRecord((int, String) data) {
Avoid positional fields in records. Use named fields instead.
19 void example2() {
20 (String, bool, int) tuple = ('test', true, 5);
Avoid positional fields in records. Use named fields instead.
25 void example3() {
26 final result = (1, 2, 3, 'four');
Avoid positional fields in records. Use named fields instead.
34 lbl: {
35 final inLabeled = (1, 2);
Avoid positional fields in records. Use named fields instead.
38 final closure = () {
39 final inClosure = (3, 4);
Avoid positional fields in records. Use named fields instead.
44
45typedef Pair = (int, String);
Avoid positional fields in records. Use named fields instead.
47void typePositions(Object value) {
48 final cast = value as (int, String);
Avoid positional fields in records. Use named fields instead.
48 final cast = value as (int, String);
49 final test = value is (int, String);
Avoid positional fields in records. Use named fields instead.
49 final test = value is (int, String);
50 final callback = ((int, String) pair) => pair;
Avoid positional fields in records. Use named fields instead.
54final callback = () {
55 final pair = (1, 2);

Valid

example.dartdart
class RecordExamples {
  /// Named fields in record literal
  void example1() {
    final record = (id: 1, name: 'hello');
    print(record);
  }

  /// Named fields in record type return
  ({int id, String name}) getInfo() {
    return (id: 42, name: 'answer');
  }

  /// Named fields in record type parameter
  void processRecord(({int id, String name}) data) {
    print(data);
  }

  /// Named fields in record type variable
  void example2() {
    ({String name, bool active, int count}) tuple = (name: 'test', active: true, count: 5);
    print(tuple);
  }

  /// Named fields in record literal with multiple
  void example3() {
    final result = (a: 1, b: 2, c: 3, d: 'four');
    print(result);
  }

  /// Record with mixed named fields
  void example4() {
    final data = (userId: 100, isActive: true);
    print(data.userId);
    print(data.isActive);
  }
}

Configure avoid-positional-fields-in-records

Set its severity in falcon.json. See the configuration guide.

falcon.jsonjson
{
  "linter": {
    "rules": {
      "style": {
        "avoid-positional-fields-in-records": "error"
      }
    }
  }
}

Or silence one occurrence with a suppression comment; the reason is required.

example.dartdart
// falcon-ignore lint/style/avoid-positional-fields-in-records: <reason>